Term
| What does the electrocardiogram do? |
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Definition
| It records differences in electrical potential (voltage) between two electrodes placed on the skin. |
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Term
| What are the principles of electrophysiology? |
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Definition
| p. 239 for all the answers. |
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Term
| How does the book define depolarization? |
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Definition
| It happens when an electrical impulse is generated in a particular area in the heart, the outside of the cell in this area becomes negative, and the inside of the cell in the same area becomes positive. This excited state of the cell, which is caused by change in polarity is called depolarization. |
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Term
| What is atrial depolarization? |
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Definition
| An instance where cardiac impulses originate in the SA node and spread to both atria. |
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Term
| How is ventricular depolarization represented on the ECG? |
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Definition
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Term
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Definition
| The return of the stimulated myocardial cells to their resting state. |
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Term
| How is ventricular repolarization represented on the ECG? |
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Definition
| by the ST segment, T wave, and U wave. |
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Term
| What does the ECG measure horizontally? |
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Definition
| Duration. Each small square is .04 second in duration. and each large square is .20 second in duration. |
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Term
| What does the ECG measure vertically? |
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Definition
| Voltages. 1mV of electrical potential registers a deflection of 10 mm in amplitude. |
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Term
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Definition
| a small positive (or negative) deflection preceding the QRS complex. |
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Term
| What is a QRS complex composed of? |
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Definition
A Q wave, which is a negative deflection of the QRS complex preceding an R wave.
An R wave is the first positive deflection of the QRS complex.
An S wave is a negative deflection of the QRS complex following an R wave. |
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Term
| What portion of the ECG is the ST segment? |
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Definition
| The portion of the ECG from the point where the S wave of the QRS ends (J Point) to the beginning of the T wave. |
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Term
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Definition
| It is measured from the beginning of the P wave to the beginning of the QRS complex, and reflects the time needed for the impulse to spread through the atria and to pass through the AV junction. |
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Term
| How long is the normal PR interval? |
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Definition
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Term
| What does it indicate if a PR interval is longer than .20 second. |
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Definition
| It indicates first-degree AV block. |
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Term
| What is the QRS interval? |
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Definition
| It is the time measured from the beginning of the first wave of the QRS complex to the end of the last wave of the QRS complex. |
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Term
| What is the normal range of a QRS interval? |
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Definition
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Term
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Definition
| It is from the beginning of the QRS complext to the end of the T wave. |
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Term
| On what do normal QT intervals depend? |
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Definition
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Term
| What could prolonged QT intervals be related to? |
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Definition
| certain drugs, electrolyte disturbances, and myocardial ischemia and infarction. |
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Term
| What does the T wave represent? |
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Definition
| Ventricular repolarization. |
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Term
| What do normal T waves lack? |
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Definition
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Term
| What may prominent peaked T waves indicate? |
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Definition
| myocardial infarction or hyperkalemia. |
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Term
| What might deep, symmetrically inverted T waves suggest? |
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Definition
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Term
| What does the U wave represent? |
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Definition
| The last phase of ventricular repolarization. |
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Term
| Where are U waves prominent? (in other words if a U wave is large, what does that indicate?) |
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Definition
| Hypokalemia and left ventricular hypertrophy. |
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Term
| What do inverted U waves suggest? |
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Definition
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Term
| What does the 12-LEAD ECG represent? |
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Definition
| 12 electrically different views of the heart recorded on special ECG paper. |
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Term
| What three groups can the 12 leads be subdivided into? |
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Definition
Bipolar standard leads I, II, and III.
Unipolar augmented leads aVR, aVL, and AVf.
Unipolar precordial leads V1-V6. |
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Term
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Definition
| i, ii, iii, aVR, aVL, and aVF are collectively called limb leads because they recard potential differences through electrodes placed on limbs. |
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Term
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Definition
| The difference in electrical potenial between the left arm (positive) and the right arm (negative) electrodes. |
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Term
| What does Lead II record? |
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Definition
| The difference in electrical potential between the left leg (positive) and right leg (negative) elctrodes. |
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Term
| What does lead III record? |
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Definition
| The difference in electrical potential between the left leg (positive) and left are (negative) electrodes. |
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Term
| What do the augmented unipolar leads record? |
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Definition
| Electrical potentials at one site relative to zero potential. |
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Term
| For lead aVR, where is the positive electrode placed? |
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Definition
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Term
| For lead aVL, where is the positive electrode placed? |
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Definition
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Term
| For lead aVF, where is the positive electrode placed? |
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Definition
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Term
| Where are the six unipolar precordial leads placed? |
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Definition
On the chest.
V1 at the fourth intercostal space on the right sternal border.
V2 at the fourth intercostal space on the left sternal border.
V3 at the midpoint of a straight line between leads V2 and V4
V4 at the fifth intercostal space, on the left midclavicular line.
V5 on the anterior axillary line and the horizontal lto lead V4.
V6 on the midaxillarly line and horizontal to leads V4 and V5. |
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Term
| What does the mean QRS axis represent? |
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Definition
| The average direction of depolarization as it travels through the ventricles, resulting in excitation and contraction of myocardial fibers. |
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Term
| How can the QRS axis be calculated? |
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Definition
By inspecting leads I, II, III, aVR, aVL, and aVF (all of the positives) and applying the following general rules:
1) The mean QRS axis is directed midway between two leads that register tall R waves of equal amplitude.
2) The mean QRS axis is directed at right angles (90degrees) to any extremity lead that registers a biphasic isoelectric complex.
a) axes between -30 and +100 are not normal.
b) an axis more negative than -30° is considered left axis deviation.
c) an axis more positive than +100° is considered right axis deviation.1 |
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Term
| How is sinus bradychardia characterize on an ECG? |
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Definition
| a normal sinus rhythm but with a heart rate less than 60 beats/minute. |
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Term
| How is sinus tachycardia characterized on an ECG? |
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Definition
| normal sinus rhythm but with an HR or 100-180 bpm. |
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Term
| How is sinus pause (sinus arrest) characterized on an ECG? |
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Definition
| Any kind of pause or absence of P wave or QRS complex during a measurement. |
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Term
| How is sinus pause (sinus arrest) characterized on an ECG? |
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Definition
| Any kind of pause or absence of P wave or QRS complex during a measurement. |
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Term
| Read "atrial flutter" and "atrial fibrillation" again |
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Definition
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Term
| What is a premature ventricular complex? |
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Definition
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Term
| What is a ventricular couplet? |
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Definition
| Two PVC's occurring in a row. |
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Term
| What is ventricular tachycardia? |
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Definition
| Three or more PVCs occuring in a row. |
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Term
| What is ventricular bigeminy? |
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Definition
| The repetitive pattern of one normal beat and one PVC. |
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Term
| What is ventricular trigeminy? |
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Definition
| The repetitive pattern of two normal beats and a PVC. |
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Term
| What is monomorphic ventricular tachycardia? |
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Definition
| It produces ventricular beats of similar morphology (appearance) |
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Term
| What is polymorphic tachycardia? |
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Definition
| It is defined by multiple forms of ventricular beats. |
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Term
| What are distinguishing features of ventricular fibrilation? |
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Definition
| a regular rhythm, a ventricular rate of 150-500 bpm, fibrillatory waves, and the absence of a distinct QRS complex. |
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Term
| How is ventricular fibrillation treated? |
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Definition
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Term
| How do atrioventricular blocks result? |
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Definition
| When supraventricular impulses are delayed or blocked in the AV node or intraventricular conduction system. |
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Term
| How is first-degree AV Block characterized? |
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Definition
| By a delay in the conduction of the impulse through the AV junction to the ventricles? |
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Term
| Does first-degree AV block impair cardiac function? |
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Definition
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Term
| What causes first-degree AV Block? |
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Definition
| Hyperkalemia, quinidine, digitalis, and ischemic heart disease. |
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Term
| What are the two types of second-degree AV Block? |
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Definition
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Term
| What is Mobitz I AV block? |
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Definition
| A situation where there is a P wave that is not followed by a QRS complex for one specific heartbeat. The next P wave is then a little smaller and nearer to the QRS complex. |
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Term
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Definition
| A delay in AV conduction at the level of the bundle branches, characterized by fixed, normal PR intercals, broad QRS complexes, and nonconducted P waves. Candidates for Mobitz II may be considered candidates for a pacemaker. |
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Term
| What is Third-Degree AV Block? |
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Definition
| (aka complete heart block). A situation where there is no conduction of impulses from the atria to the ventricles. |
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Term
| What characterizes an anterior infarction on an ECG diagram? |
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Definition
| Q waves in leads V1, V2, V3, and V4. |
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Term
| What characterizes inferior infarction in an ECG diagram? |
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Definition
| Q waves in leads II,III, and aVF |
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Term
| What characterizes lateral infarction on an ECG diagram? |
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Definition
| Q waves in leads I, aVL, V5, and V6 |
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Term
| What characterizes posterior infarction on an ECG diagram? |
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Definition
| Tall R waves in leads V1 and V2. |
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Term
| What are some causes of third degree AV block? |
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Definition
| advanced age, digitalis intoxication, or MI. |
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Term
| What is Right Bundle Branch Block? (RBBB) |
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Definition
| A situation where the QRS complex is widened (>.12 second) as a result of delayed depolarization in the right ventricle. An rSR' with a wide R wave in V1 is a characteristic ECG change associated with RBBB. |
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Term
| What is a Left Bundle Branch Block? |
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Definition
| Same is Right Bundle but on left side. A wide negative deflection (QS) is present in lead V1. V6 shows a tall R wave. |
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Term
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Definition
| Blocks involving the anterior or posterior fascicle of the main left bundle branch of the bundle.. |
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Term
| What are the two kinds of hemiblocks? |
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Definition
| Left anterior fascicular block and left posterior fascicular block. |
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Term
| On the ECG, what may signify Coronary Artery disease? |
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Definition
| A horizontal or downsloping ST depression of at least 1 mm lasting for 0.08 second. |
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Term
| What is associated with changes in both the QRS and ST-t complexes? |
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Definition
| Transmural Ischemia with MI. |
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Term
| What does subendocardial ischemia and infacrtion produce on the ECG? |
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Definition
| ST-segment depression in anterior leads, inferior leads, or both, commonly during attacks of typical angina pectoris. |
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Term
| What might sever subendocardial ischemia lead to? |
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Definition
| subendocardial infarction. |
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Term
| Don't know if I will really need to know the rest of the chapter as it deals with specific diseases on the ECG. |
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Definition
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